# eGFR Calculator
Estimate your eGFR (kidney filtration rate) from serum creatinine, age and sex with the race-free CKD-EPI 2021 equation. mg/dL or µmol/L, KDIGO stage. In your browser.
## Run it
- **CLI:** `gizza tool egfr-calc 'creatinine=1.0'`
- **Web:** https://gizza.ai/tools/egfr-calc/
- **Agents:** machine-readable descriptor (parameters JSON Schema) at https://gizza.ai/tools/egfr-calc/tool.json
## Inputs
- `creatinine` — Serum creatinine _(field)_
- `creatinine_unit` — Creatinine unit _(field)_
- `age` — Age (years) _(field)_
- `sex` — Sex _(field)_
- `equation` — Equation _(field)_
## Output
- Result (text)
## Query parameters
Open the tool pre-filled and auto-run via URL:
- `creatinine` — Serum creatinine
- `creatinine_unit` — Creatinine unit
- `age` — Age (years)
- `sex` — Sex
- `equation` — Equation
Example: `https://gizza.ai/tools/egfr-calc/?creatinine=1.0&creatinine_unit=mg%2FdL&age=50&sex=male&equation=ckd_epi_2021`
---
## About this eGFR calculator
This tool estimates your **glomerular filtration rate (eGFR)** — a measure of how well your
kidneys filter waste from your blood — from a **serum creatinine** lab value, your **age** and
your **sex**. It uses the **CKD-EPI creatinine** equations, the standard used by clinical
laboratories, and reports the result in **mL/min/1.73 m²** along with the matching **KDIGO GFR
category** (G1–G5). Everything runs locally in your browser; nothing you enter is uploaded.
By default it uses the **CKD-EPI 2021 creatinine equation**, the current race-free standard
recommended by the National Kidney Foundation and the American Society of Nephrology. You can also
select the older **CKD-EPI 2009** equation for comparison — provided here in its **race-free
form**, with the 2009 race coefficient deliberately omitted, in line with the 2021 guidance.
Enter creatinine in **mg/dL** (US) or **µmol/L** (SI); µmol/L is converted to mg/dL by dividing by
88.42 before the equation is applied.
### Worked example
Enter creatinine **1.0** mg/dL, age **50**, sex **male**, equation **CKD-EPI 2021**:
```json
{
"egfr": 92.0,
"unit": "mL/min/1.73 m²",
"equation": "ckd_epi_2021",
"creatinine_mg_dl": 1.0,
"age": 50.0,
"sex": "male",
"gfr_stage": "G1",
"stage_description": "Normal or high",
"summary": "eGFR 92 mL/min/1.73 m² (CKD-EPI 2021) — GFR category G1 (Normal or high)"
}
```
The 2021 equation gives `142 × (1.0/0.9)^−1.200 × 0.9938^50 ≈ 92` mL/min/1.73 m², which falls in
the **G1** band (≥90). A 60-year-old female with a creatinine of **1.2** mg/dL instead returns
about **52** mL/min/1.73 m² — the **G3a** band.
### KDIGO GFR categories
| Category | eGFR (mL/min/1.73 m²) | Meaning |
|---|---|---|
| **G1** | ≥ 90 | Normal or high |
| **G2** | 60–89 | Mildly decreased |
| **G3a** | 45–59 | Mildly to moderately decreased |
| **G3b** | 30–44 | Moderately to severely decreased |
| **G4** | 15–29 | Severely decreased |
| **G5** | < 15 | Kidney failure |
A **G1** or **G2** eGFR is in the normal range on its own — chronic kidney disease is only
diagnosed in those bands when there is *also* a marker of kidney damage (such as albuminuria)
present for at least three months.
### Limits & notes
- **Informational estimate, not a diagnosis or medical advice.** eGFR is an estimate; only a
clinician can interpret it alongside your full history. Do not change any treatment based on this
tool.
- **Adults only.** CKD-EPI is validated for people **18 and over**; ages under 18 are rejected —
a pediatric equation (Schwartz / CKiD) is a different calculation.
- The creatinine value should be **IDMS-standardized** (as reported by modern labs). A single
creatinine is a snapshot; eGFR can shift with hydration, muscle mass, diet and lab timing.
- **Cystatin-C equations** (2012 cystatin C, 2021 creatinine + cystatin C) need a cystatin C lab
value and are **not** included here — this is a creatinine-only calculator.
- **Race is not used.** The default 2021 equation is race-free, and the 2009 option omits the race
coefficient.
## FAQ
What is eGFR and what is a normal value?
**eGFR** (estimated glomerular filtration rate) estimates how many millilitres of blood your
kidneys filter per minute, normalized to a standard body size (1.73 m²). A value of **90 or above**
is considered normal or high (category G1). Values fall gradually with age even in healthy people.
On its own a normal eGFR doesn't rule out early kidney disease, and a single low value doesn't
confirm it — trends over months matter more than one reading.
Why does this calculator not use race?
In 2021 a National Kidney Foundation / American Society of Nephrology task force recommended
against including race in eGFR equations. This tool uses the **race-free CKD-EPI 2021** equation by
default, and when you pick the older 2009 equation it is applied in its **race-free form** (the
2009 race coefficient is left out). You get the same estimate regardless of race.
Should I enter creatinine in mg/dL or µmol/L?
Use whichever unit your lab report shows. US reports are usually in **mg/dL**; many other
countries report in **µmol/L** (SI). Pick the matching unit and the tool converts internally
(µmol/L ÷ 88.42 = mg/dL). For example, 1.0 mg/dL ≈ 88.4 µmol/L.
What's the difference between the 2021 and 2009 equations?
Both estimate eGFR from creatinine, age and sex. The **2021** equation is the current recommended
standard and is race-free by design. The **2009** equation is older and originally included a race
coefficient; here it is offered only for historical comparison and in its race-free form. The two
give slightly different numbers for the same inputs — for most people the 2021 result is what
clinical labs now report.
Can I use this for a child?
No. The CKD-EPI equations are validated for **adults (18 and older)**, so the tool rejects ages
under 18. Estimating GFR in children uses a different equation (such as the bedside Schwartz or
CKiD formula) based on height and creatinine.
Is my data sent anywhere?
No. The calculation runs entirely in your browser via WebAssembly. Nothing you enter is uploaded,
logged or stored — reload the page and it's gone.
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